Injection molding apparatus and injection molding method

Abstract

A space 12 is formed at a tip portion of a nozzle 1 so as to decrease a thermal transfer of the nozzle 1 . Alternatively, a center portion of one of a semi-spherically protruded surface of the tip portion of the nozzle 1 and a semi-spherically recessed surface of a sprue bush protrudes so that the radius of curvature of one semi-spherical surface is the same as the radius of curvature of the other semi-spherical surface. As a result, since the nozzle 1 and the sprue bush 2 are surface-contacted, heat of the tip portion of the nozzle 1 absorbed to the sprue bush 2 is increased. Thus, the temperature of the tip portion of the nozzle 1 can be lowered easily. After the resin material injected into the molding cavity 11 is cooled, when the sprue portion is removed from the fixed die, a tip portion of a rod-shaped protrusion portion of the sprue can be properly cut.

1. An injection molding apparatus having a pair of dies, a bush, and a nozzle, the bush having a receiving portion formed in a semi-spherically recessed surface, the bush having an inner resin flow path through which resin is supplied to a cavity formed by the pair of dies, the nozzle having a tip portion formed as a semi-spherically protruded surface, the semi-spherically protruded surface of the tip portion of the nozzle including a resin injection hole and being press-contacted to the semi-spherically recessed surface of the receiving portion of the bush, molten resin being injected into the cavity through the nozzle and the bush,
 wherein a center portion of the semi-spherically recessed surface of the receiving portion of the bush protrudes in a direction towards the nozzle as a protrusion portion, and 
 wherein the protrusion portion includes a semi-spherically recessed surface whose radius of curvature is the same as the radius of curvature of the semi-spherically protruded surface of the tip portion of the nozzle so that the inner resin flow path surface-contacts to only the periphery of the hole end of the resin injection hole. 
 
     
     
       2. An injection molding method for molding a molded product, comprising the steps of:
 press-contacting a semi-spherically recessed surface of a receiving portion of a bush to a semi-spherically protruded surface of a tip portion of a nozzle, the semi-spherically protruded surface including a resin injection hole, a resin flow path being formed in a cavity formed by a pair of dies, resin being supplied to the cavity through the resin flow path; and 
 injecting molten resin into the cavity through the nozzle and the bush, 
 wherein a center portion of the semi-spherically recessed surface of the receiving portion of the bush protrudes in a direction towards the nozzle as a protrusion portion, and 
 wherein the protrusion portion includes a semi-spherically recessed surface whose radius of curvature is the same as the radius of curvature of the semi-spherically protruded surface of the tip portion of the nozzle so that the inner resin flow path surface-contacts to only the periphery of the hole end of the resin injection hole. 
 
     
     
       3. An injection molding apparatus having a pair of dies, a bush, and a nozzle, the bush having a receiving portion formed in a semi-spherically recessed surface, the bush having an inner resin flow path through which resin is supplied to a cavity formed by the pair of dies, the nozzle having a tip portion formed as a semi-spherically protruded surface, the semi-spherically protruded surface of the tip portion of the nozzle including a resin injection hole and being press-contacted to the semi-spherically recessed surface of the receiving portion of the bush, molten resin being injected into the cavity through the nozzle and the bush,
 wherein a center portion of the semi-spherically protruded surface of the tip portion of the nozzle protrudes as a protrusion portion, and 
 wherein the protrusion portion includes a semi-spherically protruded surface whose radius of curvature is the same as the radius of curvature of the semi-spherically recessed surface of the receiving portion of the bush so that the inner resin flow path surface-contacts to only the periphery of the hole end of the resin injection hole. 
 
     
     
       4. An injection molding method for molding a molded product, comprising the steps of:
 press-contacting a semi-spherically recessed surface of a receiving portion of a bush to a semi-spherically protruded surface of a tip portion of a nozzle, the semi-spherically protruded surface including a resin injection hole, a resin flow path being formed in a cavity formed by a pair of dies, resin being supplied to the cavity through the resin flow path; and 
 injecting molten resin into the cavity through the nozzle and the bush, 
 wherein a center portion of the semi-spherically protruded surface of the tip portion of the nozzle protrudes as a protrusion portion, and 
 wherein the protrusion portion includes a semi-spherically protruded surface whose radius of curvature is the same as the radius of curvature of the semi-spherically recessed surface of the receiving portion of the bush so that the inner resin flow path surface-contacts to only the periphery of the hole end of the resin injection hole.